Because the password cannot be reset by hardware jumpers on this specific model, the most reliable method is to contact Dell Technical Support. Dell maintains a database of master passwords generated from your laptop's unique Service Tag.
Before proceeding, note that the Dell Latitude 5520 is a business-class laptop. The BIOS password is a designed to prevent theft. Because of this, Dell does not provide a master password override to end users. dell latitude 5520 bios password reset
Dell authorized service providers use a tool called the "Dell BIOS Recovery Tool" (DBRT). Because the password cannot be reset by hardware